Nonsteroidal anti-inflammatory drugs are the most widely used anti-inflammatory drugs in clinical practice, which are the second most consuming drugs less than anti-infective drugs in China every year. According to chemical structure, nonsteroidal anti-inflammatory drugs can be divided into the following categories: formic acid, such as aspirin; acetic acid, such as diclofenac and indomethacin; propionic acids, such as ibuprofen and naproxen; oxicams, such as piroxicam and meloxicam; coxibs, such as celecoxib and rofecoxib; pyrazolones, such asbutazodine, aminopyrine; others, such as nimesulide. These drugs can not be absorbed completely by human body after being taken, and the rest will be released into the environment with urine and faeces. Sewage treatment plants are main gathering sites. As a new type of pollutant, the existing toxicity studies have shown that the nonsteroidal anti-inflammatory drugs bring ecological toxicity on Zebrafish, Oryzias Latipe, Daphnia Magna and Lemnaceae or other aquatic organisms. The extensive use and abuse of drugs make the substance and its active components input into aquatic environment continuously. Properties of drugs (optical activity, half volatility, polarity and high toxicity etc.) and evolution law of the aquatic environment determine that the substances will transmit and spread for a long distance, then forming a universal accumulation. Thus it poses an uncertain potential threaten to human health because of the uncertainty. Therefore, it attracts more and more interests on how to remove nonsteroidal anti-inflammatory drugs in sewage treatment, systems effectively.
Study shows that the nonsteroidal anti-inflammatory drugs can not be removed from the sewage with traditional treatment techniques in sewage treatment plants, thus the drugs flow into aquatic environment along with tail water of the sewage, plant continuously and accumulate universally, and effect on aquatic ecosystems in a long time. It poses a potential threaten to aquatic environment, further influences drinking water quality directly or indirectly, and does harm to human health.
An advanced treatment process of sewage is considered as an important step of guaranteeing safe discharge of sewage. It is very important to study variety of sewage treatment technologies for removing effects on nonsteroidal anti-inflammatory drugs. Some advanced treatment processes such as activated carbon adsorption, coagulation precipitation, chlorination, can not get satisfied removal effect. For example, hydrogen peroxide has no effect on removing nonsteroidal anti-inflammatory drugs. Ozone has limited effect under present ozone dose and contact time in sewage treatment plants, and it can only remove nonsteroidal anti-inflammatory drugs partially. There is no systematic study on the use of UV-based advanced oxidation process to remove nonsteroidal anti-inflammatory drugs in actual sewage yet.